System and method for simulating contact between wheel and rail for detecting adhesion values

Abstract

A system is provided for simulating contact between wheel and rail, in particular of a railway vehicle, comprising at least one hollow cylindrical structure having a first diameter and including a rail simulation surface arranged integrally with an internal surface of the hollow cylindrical structure and at least one wheel having a second diameter smaller than the first diameter and including a rolling surface adapted to be placed in contact with the rail simulation surface of the hollow cylindrical structure.

1 . A system for simulating contact between wheel and rail, in particular of a railway vehicle, comprising:
 at least one hollow cylindrical structure having a first diameter and including a rail simulation surface arranged integrally with an internal surface of said hollow cylindrical structure;
 at least one wheel having a second diameter smaller than said first diameter, and including a rolling surface placed in contact with said rail simulation surface of the hollow cylindrical structure; 
   at least one rotation motor associated with said hollow cylindrical structure for generating a rotation of said first hollow cylindrical structure;   at least a second rotation motor associated with the at least one wheel for controlling a rotation of said at least one wheel;   at least one contaminant control system, adapted to control distribution of a contaminant on the rail simulation surface for generating a variation of a friction condition between the at least one wheel and the rail simulation surface;   at least one first sensor for torque, adapted to measure an adhesion force developed at a contact point between the at least one wheel and the at least one hollow cylindrical structure;   at least one second sensor for load, adapted to measure a normal load force on the rail simulation surface; and   a processor adapted to calculate a real wheel-rail adhesion coefficient by the ratio between the adhesion force and the normal load force.   
     
     
         2 . The system for of  claim 1 , wherein said at least one wheel is a plurality of wheels; said wheels being arranged longitudinally aligned with each other in contact with the rail simulation surface along a plane perpendicular to a rotation axis thereof for simulating a condition of rail cleaning. 
     
     
         3 . The system of  claim 1 , wherein:
 said at least one hollow cylindrical structure is at least a pair of cylindrical structures including a first hollow cylindrical structure and a second hollow cylindrical structure; the second hollow cylindrical structure being arranged along a common rotation axis thereof;   said at least one wheel is at least a pair of wheels comprising a first wheel, placed in contact with the rail simulation surface of the first hollow cylindrical structure, and a second wheel, placed in contact with the rail simulation surface of the second hollow cylindrical structure; the first wheel and the second wheel being connected to an axle.   
     
     
         4 . The system of  claim 3 , wherein the pairs of wheels are at least two and are mounted on a bogie for a railway vehicle; said pairs of wheels being arranged longitudinally aligned with each other along a plane perpendicular to the rotation axis thereof. 
     
     
         5 . The system of  claim 3 , or wherein the wheels connected to the axle are controlled through a single rotation motor. 
     
     
         6 . The system of  claim 1 , wherein each hollow cylindrical structure is rotated independently from the other by a rotation motor. 
     
     
         7 . The system of  claim 1 , wherein the contaminant control system comprises a contaminant injection system for distributing the contaminant along the rail simulation surface, a contaminant removal system adapted to remove the contaminant from the rail simulation surface, and at least one contaminant level sensor adapted to detect the level of contamination of the system for simulating the contact between wheel and rail. 
     
     
         8 . The system of  claim 7 , wherein the contaminant level sensor is at least one of either an optical sensor or a conductivity sensor. 
     
     
         9 . The system of  claim 1 , wherein each wheel is held in contact with the rail simulation surface through a force adapted to simulate a load generated by the weight of a carriage of a railway vehicle. 
     
     
         10 . The system of the preceding claims of  claim 1 , wherein to the at least one wheel is associated an electromagnetic braking system, acting directly on the rail simulation surface. 
     
     
         11 . The system of  claim 10 , wherein the electromagnetic braking system is a magnetic shoe or magnetic track brake. 
     
     
         12 . The system of  claim 1 , wherein the at least one rotation motor associated with said hollow cylindrical structure is coupled to the perimeter of said hollow cylindrical structure. 
     
     
         13 . The system of  claim 2 , comprising:
 a plurality of speed sensors, each speed sensor being adapted to detect an angular speed of one of said wheels;   a wheel slide protection system (WSP), adapted to determine slide values of the wheels whose angular speed has been detected and to apply pressure to an air tank adapted to simulate a brake cylinder for each wheel of which the angular speed has been detected, the pressure value applied to the air tank being generated as a function of slide values determined by the WSP;   a pressure/braking torque conversion system adapted to convert the pressure value detected in the air tank into respective braking torque signals for each wheel; and   a plurality of braking devices, each braking device being associated with one of said wheels of which the angular speed has been detected; each braking device being adapted to apply to its associated wheel a braking torque corresponding to the braking torque signal received from the pressure/braking torque conversion system.   
     
     
         14 . The system of  claim 13 , wherein the pressure/braking torque conversion system includes:
 a plurality of pressure transducers wherein each pressure transducer is adapted to provide an electrical pressure signal the value corresponds said electrical pressure signal corresponding to one of the pressure values applied to the air tanks by means of the WSP;   a pressure/force conversion module adapted to convert each electrical pressure signal into an electrical braking force signal; and   a force/torque conversion module adapted to convert, according to the radius of the wheels, the electrical braking force signals into respective braking torque signals to be supplied to the respective braking devices.   
     
     
         15 . A method for simulating contact between wheel and rail, in particular of a railway vehicle, comprising the steps of:
 providing at least a hollow cylindrical structure having a first diameter and including a rail simulation surface, which is arranged integrally with an inner surface of said hollow cylindrical structure;   providing inside said first hollow cylindrical structure, in contact with said rail simulation surface of the hollow cylindrical structure, at least one wheel having a second diameter smaller than said first diameter;   rotating said first hollow cylindrical structure by means of at least a first motor;   rotating the at least one wheel by at least one rotation motor associated with said at least one wheel;   injecting a contaminant substance on at least part of said rail simulation surface by means of at least one contaminant control system;   measuring an adhesion force developed at a contact point between the at least one wheel and the at least one cylindrical structure by means of at least a first sensor for torque;   checking and measuring a normal load force on the rail simulation surface by means of at least one second sensor for load; and   calculating the real wheel-rail adhesion coefficient by the ratio between the adhesion force and the normal load force.